This invention generally relates to a portable water purifier for purifying and storing drinking water, and more particularly to a purifier positionable on an existing conventional water cooling and dispensing unit.
Concern over drinking water purity and taste have prompted alternative sources of supply other than that supplied by processed tap water. This concern has been fueled by widely publicized reports of water pollution and by tap water often containing large amounts of water treatment chemicals, minerals and other matter.
One attempt to deal with this problem is the increased use of bottled waters. Sales of bottled waters which have increased substantially in recent years generally consists of a single serving to a one gallon container sold in retail establishments, and of larger containers, e.g., 5 gallon containers, sold for use with water cooler dispensers. Bottled cool water dispensers are extremely popular for both residential and commercial use because cold drinking water may be dispensed from generally a three to five gallon bottle without the need for plumbing. However, such bottled waters are expensive, and changing and storing large heavy and cumbersome bottles is burdensome.
Several problems with the quality of bottled waters also have been discovered and publicized in recent years. Bottled waters can readily become contaminated by airborne bacteria and viruses during the dispensing operation by the introduction of ambient air drawn inside the bottle as the water is dispensed. Further, the stagnant storage of bottled water allows bacteria to grow unchecked. Discoveries of dangerous chemicals and extremely high levels of bacteria in bottled waters has led many to the conclusion that bottled water may be no more pure, or sometimes even less pure, than ordinary tap water. Such problems with tap and bottled water have revealed a need and desire for water treatment at the point of use.
Several point of use treatment alternatives exist to tap and bottled water and are well known in the art. One such alternative is the use of carbon filtration. Carbon filters use activated charcoal to remove impurities consisting mostly of organic compounds and to improve the taste of water. Carbon filters, however, are generally ineffective in removing most inorganic compounds such as lead and arsenic.
Another alternative known in the art is the use of reverse osmosis to treat the water. Reverse osmosis units use a sediment prefilter. These units however, have a tendency to become clogged by high levels of hardness minerals and thus are not feasible for some geographic locations. Other problems with reverse osmosis include the waste of approximately 80% of the feedwater, the great expense of replacement membranes and the requirement of pressurized water feed lines and water drain lines which eliminates portability.
Another alternative point of use water treatment method is distillation. Distillation devices purify water by boiling water to generate steam, and then condense the steam to form water free from such contaminants. The contaminants having a vaporization temperature higher than that of water remain in the boiling pot, while solvents which have a boiling point lower than water may be separated from the steam by venting before condensation. The distillation process is more effective in removing impurities than reverse osmosis and does not have the problem of water waste.
Distillation devices may be portable, without the need for pressurized feed lines and drain lines or non-portable which require feed lines to supply water. Distillation alone, however, is relatively ineffective in removing volatile chemicals such as benzene and chlorine.
Existing portable distillers and most non-portable devices have failed to adequately deal with the problem of scale deposits in, and cleaning of, the boiling pot, as for example, the portable distillation device shown in U.S. Pat. No. 4,342,623 which has no provision to inhibit scale build-up. Other prior art portable distillation devices have a removable boiling pot, but require partial disassembly of the unit for removal of the boiling pot. Additionally, the known distillation units include a float valve within the boiling pot or tank, such as U.S. Pat. No. 4,943,353 which is thus exposed to the build-up of scale. When excessive scale deposits occur failure of the float valve may result which may cause an overheating situation and a system failure.
Distillation units in the prior art are of the type wherein the water is distilled and captured for subsequent use, such as illustrated in U.S. Pat. No. 4,342,623; of the type wherein uncooled water may be dispensed as illustrated in U.S. Pat. No. 4,622,102; or of the type wherein the distillation unit is coupled with refrigeration such as illustrated in U.S. Pat. No. 3,055,810. As aforesaid, bottled water dispensers are extremely popular. It would thus be advantageous to replace the water bottles of such containers with a less expensive and purer water source such as an efficient distillation unit.
In copending U.S. patent application Ser. No. 07/902,703 filed Jun. 23, 1992, a water purification apparatus is disclosed which is mounted within a housing adapted to be positioned on a conventional water cooler/dispenser. The apparatus includes a valve control member which extends from the housing and is positionable within the water reservoir of the dispenser to control the release of purified water from the apparatus to the reservoir. To provide a compact housing for the water purification apparatus requires a boiler having a small cross section. In order to provide a high energy heating element in the boiler which is necessary for providing sufficient on demand purified water for the unit a boiler with an extended length is normally required to prevent a condition known as carry-over, i.e., where the water in the boiler surges or flash vaporizes upwardly into the condenser coil, a condition which obviously is unsatisfactory. Thus, the height of the boiler disclosed in the aforesaid patent application was extended. This resulted in the height of the housing being greater than desirable. Additionally, in the apparatus disclosed in the aforesaid copending patent application the level of the water within the boiler was controlled by the water level in the feedwater tank which is at an upper portion of the apparatus so that the height of the boiler had to be great enough to prevent water within the boiler from flowing or flashing into the condenser. It is obviously desirable to reduce the height of the boiler so that the height of the entire apparatus may be reduced to provide a compact unit.